FAILED: patch "[PATCH] drm/rockchip: vop: clear DMA stop bit on RK3066" failed to apply to 5.15-stable tree

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 6b44aa559d6c7f4ea591ef9d2352a7250138d62a
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2024100707-brunch-thumb-0511@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

6b44aa559d6c ("drm/rockchip: vop: clear DMA stop bit on RK3066")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 6b44aa559d6c7f4ea591ef9d2352a7250138d62a Mon Sep 17 00:00:00 2001
From: Val Packett <[email protected]>
Date: Mon, 24 Jun 2024 17:40:48 -0300
Subject: [PATCH] drm/rockchip: vop: clear DMA stop bit on RK3066

The RK3066 VOP sets a dma_stop bit when it's done scanning out a frame and needs the driver to acknowledge that by clearing the bit.

Unless we clear it "between" frames, the RGB output only shows noise instead of the picture. atomic_flush is the place for it that least affects other code (doing it on vblank would require converting all other usages of the reg_lock to spin_(un)lock_irq, which would affect performance for everyone).

This seems to be a redundant synchronization mechanism that was removed in later iterations of the VOP hardware block.

index a13473b2d54c..e88fbd5685a3 100644
@@ -1583,6 +1583,10 @@ static void vop_crtc_atomic_flush(struct drm_crtc *crtc,
 	VOP_AFBC_SET(vop, enable, s->enable_afbc);
 	vop_cfg_done(vop);
 
+	/* Ack the DMA transfer of the previous frame (RK3066). */
+	if (VOP_HAS_REG(vop, common, dma_stop))
+		VOP_REG_SET(vop, common, dma_stop, 0);
+
 	spin_unlock(&vop->reg_lock);
 
 	/*

index b33e5bdc26be..0cf512cc1614 100644
@@ -122,6 +122,7 @@ struct vop_common {
 	struct vop_reg lut_buffer_index;
 	struct vop_reg gate_en;
 	struct vop_reg mmu_en;
+	struct vop_reg dma_stop;
 	struct vop_reg out_mode;
 	struct vop_reg standby;
 };

index b9ee02061d5b..9bcb40a640af 100644
@@ -466,6 +466,7 @@ static const struct vop_output rk3066_output = {
 };
 
 static const struct vop_common rk3066_common = {
+	.dma_stop = VOP_REG(RK3066_SYS_CTRL0, 0x1, 0),
 	.standby = VOP_REG(RK3066_SYS_CTRL0, 0x1, 1),
 	.out_mode = VOP_REG(RK3066_DSP_CTRL0, 0xf, 0),
 	.cfg_done = VOP_REG(RK3066_REG_CFG_DONE, 0x1, 0),